1. Field of the Invention
The present invention relates to a testing method and tester which are used for a hard disk drive (HDD) or the like, and particularly to a tester and a testing method in which a defective portion on a disk is detected in the manufacturing process of a magnetic disk drive, and a flagging is performed so that the particular portion is not used.
2. Description of Related Art
In the HDD used as the external storage device of an information processing unit, more miniaturization and reliability are required. Specifically, in the manufacturing process (test process) of a magnetic disk unit, there is a process for finding a defect such as a flaw occurring in a disk before the shipment, and performing a flagging so that the particular portion is not used. This process is called a Surface Analysis Test (SAT), which is a test for finding a defect on a disk and performing a flagging so that the particular portion cannot be used.
A flaw or the like having occurred in a disk is determined to be a defect when it cannot be read or written in an actual read/writing operation, and a flagging is performed so that the corresponding area is not used after shipped, thereby making the corresponding area invisible from the outside (unusable). Expecting the occurrence of defects in the disk, a predetermined amount of buffer is reserved, and the flagging is performed until the buffer is exhausted. The disk is determined to be a failure if the buffer is exhausted.
In the conventional SAT, the flagging is performed as follows.
In reading, if a read is performed and a plurality of errors occur in the same sector, that sector is flagged regardless of position in the sector. A read is performed, and, for instance, an error up to one per one megabyte is allowed.
In writing, if a write is performed and a plurality of errors occur in the same cylinder, that cylinder is flagged (or on a track basis) regardless of position in the cylinder. Generally, most of the write errors are caused by a servo trouble. Since the servo trouble causes errors in a plurality of portions rather than one portion, the use of the cylinder itself is inhibited.
In the SAT of the conventional disk drive, a sector is flagged if a plurality of errors occur in the same sector when a read is performed; and a cylinder is flagged if a plurality of errors occur in the same cylinder when a write is performed. Accordingly, sectors/cylinders which need not be flagged depending on the contents of the error are flagged and increase flagging results in the increase of disk failures, leading to reduction in the throughput.
It is the object of the present invention to provide a testing method and tester which can reliably flag errors which need to be flagged, and can largely decrease flags which are not necessary, thereby enabling disk failures to be reduced.